Hot air gun



May 26, 193 A. F. LEVENHAG'EN EOT AIR GUN Filed Feb'. 12, 19555 Patented May 26, 1936 UNITED STATES PATENT OFFICE 9 Claims.

Thisinvention relates to a hot air gun by means of which air may be heated and directed into a crank case or transmission housing for softening grease and oil which have hardened due to low temperatures or other reasons and allow the old oil or grease to be withdrawn when replenishing is necessary or softened sufiiciently to permit an automobile to be started easily during cold weather after standing for some length of time.

At the present time guns for this purpose are in use but they have not been found satisfactory as the air passes directly into a heating chamber from which it is expelled after being heated and as walls of the heating chamber are not insulated, the whole gun becomes overheated thereby making the gun too hot to be conveniently handled. The fact that the air passes directly into the heating chamber is also objectionable as the air is cold when it enters the chamber and, therefore, does not become heated to as high a temperature as desired for quick and thorough softening of the oil and grease.

Therefore, one object of the invention is to provide a gun of such construction that the incoming air passes through a chamber surrounding the heating chamber before entering the heating chamber, thus providing an air jacket about the heating chamber 50 that the outer 3o walls of the gun will not become overheated when the gun is in use and also causing the air to be preheated before entering the heating chamber. It will thus be seen that walls of the heating chamber itself will be enclosed in a jacket through which air passes and prevented from being cooled by exposure to atmospheric temperatures and as the air is preheated before it enters the heating chamber, it will be very hot when discharged from the gun.

Another object of the invention is to so construct the gun that it may be conveniently held when in use by a handle at its rear end, the handle serving not only as means for holding the gun but also as a conduit through which 5 electric wires pass for supplying current to the heater.

Another object of the invention is to permit the gun to be easily connected with the valve engaging terminal of a tube employed at practically all service stations and garages for inflating tires, thus making it unnecessary to provide special equipment for supplying air to the air gun.

Another object of the invention is to so con- 5 struct the gun that while under normal conditions its parts will be securely held assembled and they may be easily taken apart when cleaning or renewal of parts is necessary.

The invention is illustrated in the accompanying drawing, wherein Figure 1 is a longitudinal sectional view through the improved hot air gun.

Figure 2 is a sectional view, taken transversely through the gun along the line 2-2 of Figure 1,

This improved gun has a cylindrical barrel l which is formed of steel or other suitable material which will be strong and at the same time of light weight. This barrel extends between heads 2 and 3 with its ends engaged about sleeves 4 and 5 forming part of the heads, and within the barrel is fitted a liner 6 which may be of asbestos, lava, or any other suitable material which will serve to resist radiation of heat from within the barrel. The heads 2 and 3 are of appreciably greater diameter than the barrel l and engage opposite end portions of a cylindrical jacket I which is also formed of steel or other light but strong material, the head 2 being formed with an internally threaded flange B which has threaded engagement with the forward end of the jacket and the head 3 fitting snugly within the rear end of the jacket. There has also been provided a handle 9 which abuts the head 3 on the rear end of the jacket I and is formed with an internally threaded flange H) which has threaded engagement with the rear end of the jacket. It will thus be seen that when assembling this gun the barrel and its liner may be applied to the sleeve 5 of the rear head with the ports ll of the barrel and liner in registry, the jacket fitted into place about the rear head, the front head then applied with its sleeve 4 fitted into the front end of the barrel, and its flange 8 screwed upon the front end of the jacket. The head of the handle is then screwed on to the rear end of the jacket until it has abutting engagement with the rear head to force this head and the barrel and liner forwardly into tight fitting engagement with the sleeve of the front head.

In order to heat the air, there has been provided a heater l2 which includes a core l3 formed of porcelain or other suitable insulating material. About this core is wound a heating coil I4, the ends of which are connected to conductors M which extend longitudinally through the core and at their rear ends are engaged with terminal screws l5 to which the conductors l6 of a power line H are attached. This power line or wire ll extends through the grip l8 and upper arm I9 of the handle which are hollow, and it will be understood that the conductor wires are connected with the terminal screws before the handle is applied to the jacket 1. By referring to Figure 1, it will also be seen that the shank 23 of the core I3 is formed with an enlargement or collar 21 which bears against an internal fiange 22 formed in the head 3 and that back of the collar 2| the shank is enlarged and threaded to receive a securing ring 23 which, when screwed into place, bears against the rear face of the flange 22 and causes this flange to be firmly gripped between the ring and the collar 2|. Therefore, the heater will be securely held in place but may be removed by unscrewing the ring. As the terminal screws are disposed externally of the heating chamber, the wires of the power line will not enter this chamber and there will be no danger of the wires being burnt off at their connection with the terminals.

Air is to be delivered into the chamber between the barrel and the jacket I and this air passes inwardly through a tube or nozzle 25 which extends longitudinally in the chamber 24 and has its rear end portion threaded, as shown at 26, and engaged through alined threaded openings formed in the head 3 and handle 9. A securing nut 2'! is applied to the projecting outer end of the nozzle to securely hold the nozzle in place and beyond this securing nut the protruding end of the nozzle is engaged by a valve 28 having a nipple 29 extending from it for engagement by the terminal 33 of an air hose 3| used at practically all garages and service stations for inflating tires. The lower arm 32 of the handle terminates in an upturned end portion 33 through which a threaded opening is formed and through this opening is engaged a set screw 34 having a head at its forward end for engaging the terminal 30 and holding the terminal firmly in engagement with the nipple 29. It will thus be seen that when the terminal is secured against the nipple, air from the hose 3! may pass through the tube 24 to a point adjacent the forward end of the chamber 24. After leaving the nozzle or tube 25, the air will pass upwardly around the cylinder I and rearwardly through the chamber 24 until it reaches the rear end portion of this chamber where it will pass inwardly through the openings ll into the heating chamber. Heat radiated from the cylinder I will be absorbed by the air moving through the chamber 24 and thus the gun will be prevented from becoming too hot to handle, while at the same time the air as it passes through the chamber 24 will be preheated and enter the heating chamber as preheated air instead of as cold air. By this arrangement the air which moves forwardly through the heating chamber about the heating unit will be heated to a high temperature and be discharged as very hot air.

The forward head 2 of the gun has a portion 35 which tapers forwardly and terminates in an externally threaded neck 36 to which the rear end of a nozzle 31 is detachably connected by a coupling 38. This nozzle or spout 31 has been shown curved longitudinally but it will be understood that it may be straight or a fiexible spout and may be of any length desired. During use of the gun, the nozzle or spout is thrust into the filling opening through which grease or oil is fed into a transmission casing or crank case of an automobile and the very hot air passing from the heating chamber through the spout will be fed directly into the gear housing or crank case.

This hot air will soften oil or grease which has thickened due to low temperatures and permit the automobile to be started easily. It will be obvious that the device may be also used for thawing a carbureter or other portions of an automobile which have been rendered inoperative due to low temperatures and also that the device is not limited to use in connection with portions of an automobile as it may be used for delivering a jet of hot air at any place desired. When it is necessary to clean or repair parts of the air gun it may be very easily taken apart, the repairs made and again assembled.

Having thus described the invention, what is claimed as new is:

1. A hot air gun comprising a cylinder defining a heating chamber and having an inlet in its rear portion and an outlet at its front, a cylindrical jacket surrounding said cylinder in spaced relation thereto and defining an outer chamber, a heating unit mounted in the heating chamber between the inlet and front end thereof, and an air inlet tube extending longitudinally in the outer chamber and having its rear portion adapted for connection with the supply pipe and its forward end terminating adjacent but in spaced relation to the front end of the outer chamber whereby air will be delivered through the tube into the forward end portion of the outer chamber in spaced relation to the inlet of the heating chamber longitudinally of the outer chamber and be preheated as it moves rearwardly through the outer chamber to the inlet of the heating chamber.

2. A hot air gun comprising a cylinder defining a heating chamber and having a side inlet adja- 1 cent its rear end, front and rear heads for said cylinder having portions projecting radially therefrom, a cylindrical casing disposed about the cylinder in spaced relation thereto to define an outer chamber with its end portions engaging the front and rear heads, a heating unit carried by the rear head and extending into the heating chamber beyond the inlet, the forward head being formed with an outlet for the heating chamber, and a tube extending longitudinally in the outer chamber with its rear end projecting through the rear head for connection with a supply pipe and its forward end terminating adjacent the forward end of the outer chamber whereby air will be delivered into the forward end of the outer chamber and be preheated by absorbing heat from the cylinder as it passes rearwardly through the outer chamber to the inlet of the heating chamber.

3. A hot air gun comprising a cylinder defining a heating chamber, the heating chamber being formed with an inlet opening in its side adjacent its rear end, front and rear heads having sleeves entering the cylinder, a cylindrical jacket about said cylinder spaced therefrom to define an outer chamber surrounding the cylinder, said jacket l having its front end detachably connected with the front head and its rear end surrounding the rear head, the front head being formed with an outlet for the heating chamber, a heating unit removably secured in the sleeve of the rear head and extending forwardly in the heating chamber beyond the inlet, a handle having a head at its front end detachably engaging the rear end of the jacket and abutting the rear head of the cylinder, conductor wires connected with terminals of the heating unit, and a tube extending longitudinally in the outer chamber with its rear end projecting through the rear head and head of said handle for connection with a. supply Gil pipe and its front end terminating adjacent the front end of the outer chamber whereby air passing through the tube will be delivered into the front end of the outer chamber and absorb heat from the cylinder as it passes rearwardly through the outer chamber to the inlet of the heating chamber.

4. A hot air gun comprising a cylinder defining a heating chamber, a liner for the heating chamber, the heating chamber being formed with a side inlet in its rear end portion, front and rear heads having sleeves entering the cylinder and abutting front and rear ends of the liner to hold the liner in place, the front head being formed with an outlet for the heating chamber, a cylindrical jacket surrounding said cylinder in spaced relation thereto to define an outer chamber and having its front end detachably connected with the front head and its rear end fitting snugly about the rear head, a heating unit extending through the sleeve of the rear head into the heating chamber, the portion of the heating unit in the sleeve of the rear head being formed with an annular seat, an annular rib carried by the sleeve of the rear head and engaged in the seat to hold the heating unit in place, and means for conducting air into the outer chamber and delivering the air into the forward end of the outer chamber.

5. A hot air gun comprising a cylinder, front and rear heads engaging ends of the cylinder and of greater diameter than the cylinder, a cylindrical jacket surrounding said cylinder with its front end detachably engaged with the front head and its rear end fitting snugly about the rear head, the heating chamber defined by said cylinder having a side opening through the rear end portion of the cylinder to establish communication between the heating chamber and the outer chamber defined by said jacket, a heating unit secured in the rear head and projecting into the heating chamber, a handle having a grip and upper and lower arms extending forwardly therefrom, the grip and upper arm being hollow and the upper arm terminating at its front end in a head abutting the rear head of the cylinder and detachably engaging the rear end portions of said jacket, power wires extending through the hollow grip and upper arm and connected with terminals of the heating unit, a tube extending longitudinally in the outer chamber with its rear end projecting through the rear head and the head of said handle for engagement by a terminal of a supply pipe, a fastener carried by the forward end of the lower arm of said handle for holding the terminal of the supply pipe in engagement with the rear end of said tube, said tube terminating adjacent the forward end of the outer chamber whereby air will be delivered into the forward end of the chamber and absorb heat from the cylinder as it moves rearwardly to the inlet of the heating chamber.

6. A hot air gun comprising a cylinder defining a heating chamber, the heating chamber having an inlet adjacent its rear end, front and rear heads, the front head being formed with an outlet for the heating chamber and the rear head having a sleeve entering the cylinder, a jacket surrounding said cylinder in spaced relation thereto to define an outer chamber and having its end portions engaging said heads, a heating unit extending through said sleeve into the heating chamber beyond the air inlet thereof, and means for delivering air into the outer chamber a-djacent the forward end thereof.

'7. A hot air gun including inner and outer cylinders defining an inner chamber and an outer chamber surrounding the inner chamber, the inner chamber having an outlet at its front end and adjacent its rear end communicating with the outer chamber, a head closing the rear end of the outer chamber and having a sleeve constituting an extension of the inner cylinder, a heating unit extending through said sleeve into the inner chamber, the portion of the heating unit in the sleeve being formed with an annular seat, an annular rib carried by said sleeve and engaged in the seat to hold the heating unit in place, and means for delivering air into the front end portion of the outer chamber.

8. A hot air gun including an inner chamber, an outer chamber surrounding the inner chamber, the inner chamber having an outlet at its front end and adjacent its rear end communicating with the outer chamber, a head for the rear end of the outer chamber, a heating unit extending through the rear head into the inner chamber, an annular rib carried by said head, a collar carried by said heating unit and abutting the front face of said rib, a securing ring threaded upon the heating unit and abutting the rear face of said rib to securely but detachably hold the heating unit in place, and means for delivering air into the front end portion of the outer chamber.

9. A hot air gun including an inner chamber, an 'outer chamber surrounding the inner chamber, the inner chamber having an outlet at its front end and adjacent its rear end communicating with the outer chamber, a head for the rear end of the outer chamber, a heating unit extending through the rear head into the inner chamber, a removable handle abutting the rear head and formed with a passage having one end facing the rear end of the heating unit, terminals at the said rear end of the heating unit, conductors extending through the passage of the handle and attached to said terminals, and means for delivering air into the forward portion of the outer chamber.

ALEXANDER F. LEVENHAGEN. 

